Camera Rotation in World Coordinates?
The transform properties display LOCAL coordinates.

The values for location, rotation and scale are local coordinates. 

They will also be the global coordinates if camera has no parent, or all its ancestors have Identity  matrix world (0 loc and rot unit scale) (and there are no constraints involved)  

To display the global location of an object snap the 3d cursor to the object. (ShiftS Cursor to active) The 3d cursor is always in global coordinates.

In cases where you can set the global location of camera, move the 3d cursor and (ShiftS Active to Cursor)  Note if there are constraints (for example copy location) then these will override any transform property settings.

Can get the global rotation from the console with 

&gt;&gt;&gt; C.object.matrix_world.to_euler()
Euler((0.7297371029853821, -0.4792802035808563, -0.5616455078125), 'XYZ')


that's in radians. In degrees

&gt;&gt;&gt; [degrees(a) for a in C.object.matrix_world.to_euler()]
[41.8108561551659, -27.460732869353954, -32.179917180138155]


Displaying in the UI. 


Cube rotated locally in y 45 degrees. Parented to empty.  The global rotation is displayed below the local. (The Cube is pinned to properties, as the empty  parent is rotated)

Bare bones example script for 2.8 to put  global rotation euler 'XYZ' on transform panel.  Didn't add a setter, hence the disabled look. 

import bpy
from mathutils import Vector
from bpy.props import PointerProperty, FloatVectorProperty, IntProperty
def global_rotation_euler(self):
    ob = self.id_data
    return ob.matrix_world.to_euler() # ob.rotation_type


from bpy.types import PropertyGroup
class GlobalCoords(PropertyGroup):
    x : IntProperty()
    rotation_euler : FloatVectorProperty(name="Rotation",
            default=(0, 0, 0),
            size=3, 
            subtype='EULER', 
            precision=3,
            get=global_rotation_euler)

bpy.utils.register_class(GlobalCoords)

bpy.types.Object.global_coords = PointerProperty(type=GlobalCoords)

def draw_global_coords(self, context):
    ob = context.object
    layout = self.layout
    col = layout.column()
    col.prop(ob.global_coords, "rotation_euler")

bpy.types.OBJECT_PT_transform.append(draw_global_coords)